Stenoses in body lumens are often treated by balloon catheter dilatation, sometimes followed or accompanied by the application of heat. A balloon at the end of a catheter is positioned at the obstruction (in a blood vessel, typically plaque) and inflated. The pressure of the balloon against the wall of the lumen or obstructing material supplies a force to widen the lumen. A problem that sometimes occurs with dilatation is damage to the lumen tissue or reocclusion because of reaction of the lumen tissue to the dilatation. An example is intimal hyperplasia. Also, plaque material in arteries sometimes fractures or cracks under pressure of the angioplasty balloon, leaving rough surfaces that encourage further deposits, thrombosis and reocclusion.